The present invention pertains generally to arbor nuts. More particularly, the new and useful invention claimed in this document pertains to a self-aligning arbor system that overcomes unwanted effects of various forces on a rotor, drum such as a brake drum, adapter components, and related components on a rotating arbor. The present invention is particularly, but not exclusively, useful for use in connection with arbors on vehicular brake lathes.
A motor vehicle brake is any mechanical device for arresting the motion of a wheel or a vehicle by means of friction. Kinetic energy is converted into heat energy through the use of frictional force applied to the wheels, causing a car to slow or stop. One component of a modern motor vehicle brake is a brake disc, which is the rotating part of a disc brake; the disc often is called a rotor. Another component of a drum brake system is a drum-shaped metal cylinder attached to the inner surface of the wheel that rotates with the wheel. See, for example, The Road and Track Illustrated Automotive Dictionary, (copyright) 2000 John Dinkel, Bentley Publishers, pages 66 and 72. Due to significant heat, to forces applied during braking, and to the environment in which brake systems operate, rotors are subjected to warp, damage, and wear, yet may be correctable and repairable. A rotor or drum may be resurfaced, refinished or otherwise ground or shaped (collectively, xe2x80x9cresurfacedxe2x80x9d) on a brake lathe. While the present invention is useful in connection with resurfacing at least disks and drums of vehicular brakes, to avoid repetition, primary reference will be made to rotors in this document.
Resurfacing a rotor results in a less expensive aftermarket replacement part. An exemplary brake lathe adapter system for securing a workpiece like a rotor to a rotatable machine member such as an arbor used in the resurfacing process is disclosed in U.S. application Ser. No. 09/394,381, filed on Sep. 9, 1999, since issued as U.S. Pat. No. 6,279,919 B1, issued Aug. 28, 2001, a document incorporated by reference into this document, which names as the sole inventor the inventor of the present invention. Using a brake lathe to resurface, refinish or otherwise work on a rotor associated with a brake system of a car, truck, or other motor vehicles is a major after-market industry in the United States. At least one report of the Automotive Market Research Council indicated projections of sales of aftermarket brake products would increase almost 11% between 1997 and 2000. In the year 2000, sales of drums and rotors were projected to approximate $938,000,000.
Annually, a significant portion of brake rotors and drums are resurfaced, refinished or otherwise worked on by mounting a rotor on a shaft ( frequently called an xe2x80x9carborxe2x80x9d) of a brake lathe machine, securing the brake rotor in a brake lathe adapter, causing the arbor to rotate, and applying one or more tools to the surface of the rotor to resurface, refinish or otherwise perform work on one or more surfaces of the rotor.
At least one of the purposes of a brake lathe adapter and an arbor nut, or arbor locking nut, is to ensure parallelism in a resurfaced rotor. Tolerances are frequently as demanding as plus-or-minus 0.001 inch. Objectives include eliminating runout and taper of the rotor surface, also known as wobbling. Spacers and adapters may be used to keep a rotor""s axis substantially perpendicular to the longitudinal axis of the rotating arbor. Excessive torque applied to an locking arbor nut also may significantly affect the parallelism of a refinished rotor.
During refinishing or resurfacing of a rotating workpiece mounted on a rotatable shaft, a rotor and an arbor may be subjected to a variety of forces, and phenomena resulting from such forces. In general, forces due to rotation and gravity tend to preclude uniform rotation of a rotating shaft and a rotating workpiece such as a rotor in a single, unvarying plane of rotation. If the workpiece is a rotor or drum, such as a brake rotor or brake drum mounted on a rotating arbor of a machine such as a lathe, forces acting on the arbor and workpiece during rotation of the arbor and workpiece may distort one or more planes and axes of rotation in connection with the rotor, and exert a variety of angular and planar forces that may affect how accurately and quickly an operator of the lathe may work on the rotor. Forces and force vectors may cause harmonics and vibrations that may be transmitted to the shaft, rotor and other components of the lathe during rotation. Any nonuniform rotation of a rotor during a resurfacing operation may cause a cutting tool brought in contact with a rotor to produce an inferior surface on a working area or surface of a rotor.
During operation of a brake lathe arbor forces include gravity, friction, velocity of rotation, and a variety of load forces applied during operation to bearings, driven shafts, turning spindles, retaining devices, locking nuts, and other components of driving machines and driven shafts (collectively, xe2x80x9cmachine membersxe2x80x9d). Similar forces may be induced in a rotor. For example, circular rotation of arbors may give rise to centripetal force, a force that may be reacted to by centrifugal reaction. Angular velocity and angular acceleration of rotating workpieces subjected not only to varying velocities during operation, but also to differing loads or pressures, also may cause gyroscopic effects on a rotor that may turn or rotate over a range of different speeds. Machine members and workpieces also may be subjected to significant loads about their geometric and rotational axes. When more than one force act on a rotatable arbor, a torque may be formed whose vector along an x-axis may produce a rotation about the y-axis known as precession. Such rotation may generate significant angular velocities. All of the foregoing forces, phenomena, torque and related effects (collectively, xe2x80x9cforcesxe2x80x9d) may individually and collectively contribute to causing nonuniform rotation of an arbor and a workpiece attached to an arbor.
In addition to such forces, angular accelerations and velocities may be present in connection with rotating machine members, leading to unbalanced forces that may induce high harmonics, chattering, and vibrations. In some but not all instances, if the speed of rotation of a shaft is slowly increased from rest, a speed may be achieved at which a deflection increases suddenly, a phenomenon known as xe2x80x9cwhirling.xe2x80x9d A shaft that is balanced will rotate around the center of gravity or axis of rotation of a shaft. A shaft rotating at an angular velocity, however, may deflect a distance from the center of gravity or axis of rotation due to centripetal reaction. An unbalanced shaft, for example an arbor that has been deflected or bent and therefore does not rotate around a true center of rotation, also presents additional rotational problems. Rotation also may induce undamped free vibrations.
A variety of apparatus have been proposed to reduce or eliminate such forces and phenomena, seeking to enable a machine operator, including a brake lathe operator, to more effectively resurface a rotating workpiece such as a brake rotor. As indicated, an exemplary solution to the problems is presented by the brake lathe adaptor system disclosed in U.S. application Ser. No. 09/394,381 since issued as U.S. Pat. No. 6,279,919 B1, issued Aug. 28, 2001.
Overlooked, however, until now, among components other than a brake lather adaptor system for an effective brake lathe system has been the arbor nut, or arbor locking nut (collectively, xe2x80x9carbor nutxe2x80x9d). At least one objective of the components, individually or collectively, used to position a rotor on an arbor is to position the rotor during operation substantially perpendicular to the rotating arbor. In turn, that objective seeks to overcome the inherent effect of forces that induce vibration and chattering in the rotor. The typical conventional arbor nut is not capable of applying a consistent, predictable, uniform force against brake lather adapter components along the longitudinal axis of the arbor in the direction of the brake lather adapter components (xe2x80x9clateral forcexe2x80x9d). In addition, a common unwanted occurrence during a resurfacing operation is for a brake lathe operator to apply too much torque to tightening a conventional arbor nut. An arbor nut placed too tightly against one of the components of a brake lathe adapter may induce unwanted forces that the brake lather adapter has overcome. Also, over-tightening an arbor nut can also bend or otherwise distort the arbor itself during rotation. A distortion of the arbor may reduce the effectiveness of the brake lathe adapter in controlling the unwanted forces. A distorted arbor also may make the brake lather nonoperational without a brake lathe operator being aware of the problem. The conventional arbor nut does not compensate for a bent or otherwise distorted arbor.
At least one prior approach for solving the problem suggests use of two components, a conventional arbor nut, and a spacer-adapter. The spacer-adapter may be located on the arbor between the arbor nut and the first surface of the components assembled to hold the rotor in place on the arbor. However, because there are two separate components, angular offsets in planes perpendicular to the arbor may vary significantly in either direction of possible rotation around an axis through the longitudinal axis through the arbor.
Therefore, a previously unaddressed need exists in the industry for a new and useful self-aligning arbor nut system, and method for making the apparatus, that achieves at least three objectives: It should be self-aligning; it should, for example, compensate for a bent or distorted arbor to enable the operator of a brake lathe to repetitively produce a parallel resurfaced brake rotor. It should be hand-tightenable against a workpiece on a rotor. It should contribute to over-all safety during operation of a brake lathe. There exists a need for a self-aligning arbor nut system capable of preventing application of over-torque on an arbor nut. Particularly, there is a significant need for a method and apparatus that contributes to overcoming the unwanted effects of forces that induce vibration and chattering in the rotor. Also useful would be a self-aligning arbor nut system capable of applying a consistent, predictable, uniform lateral force against the brake lather adapter components along the longitudinal axis of the arbor in the direction of the brake lather adapter components, and to compensate for a bent or distorted arbor. A self-aligning arbor nut system should allow an operator of a brake lathe to apply the appropriate amount of torque when tightening the arbor nut system. Such an arbor nut system would not induce unwanted forces that the brake lather adapter has overcome, and would not bend or otherwise distort the arbor itself during rotation.
Given the conventional solutions for solving the problem of overcoming the unwanted effects of various forces on a rotor, adapter components, and a rotating arbor, it would be desirable, and of considerable advantage, to provide a self-aligning arbor nut system that is alignable by hand, so as to reduce the undesirable results of over-torquing a conventional arbor nut that is tightened onto an arbor using a large wrench. It would also be advantageous to provide such a self-aligning arbor nut system that could be removed from the arbor by hand, but also could be removable by use of a key or similar tool.
The present invention provides numerous advantages in overcoming unwanted effects of various forces on a rotor, adapter components, and a rotating arbor. At least one advantage of the present invention is that it contributes to positioning a rotor by hand on an arbor during operation of a rotatable arbor to hold a work piece substantially perpendicular to the rotating arbor. Accordingly, the present invention helps overcomes the effect of forces that induce vibration and chattering in the rotating work piece, such as a brake rotor. Another advantage of the self-aligning arbor nut system is its capability to apply consistent, predictable, uniform forces against other components mounted on a rotor, including components of a brake lather adapter. Yet another advantage of the present invention is its ability to hold components in place along the longitudinal axis of the arbor in the direction of the brake lather adapter components, thus helping to overcome chatter and similar movement in a rotor. Still another advantage of the self-aligning arbor system is solution for avoiding application of too much torque by an operator of a brake lathe when mounting the self-aligning arbor nut system on an arbor. An arbor nut placed too tightly against a component of a brake lathe adapter may induce unwanted forces that the brake lather adapter has overcome. The self-aligning arbor nut system of the present invention also helps prevent distortion or bend in the arbor. The present invention contributes to overall safety in the use of brake lathes by providing a surface for the apparatus that is cylindrical rather than edged due to the hexagonal shape of the typical conventional arbor nut, thus helping to prevent injury caused by those edges if the body of an operator or user of the invention should come in contact with the rotating nut. Yet another advantage of the present invention is a self-aligning arbor system, and a method for making and manufacturing a self-aligning arbor system, which respectively are easy to use and to practice, and which are cost effective for their intended purposes.
These and other advantages are achieved in the present invention by providing a self-aligning arbor system that includes a body formed with a duct substantially coincident with the longitudinal axis of the body. A ring known as a swivel also is provided. The ring is engageable with at least one end of the duct and with the arbor using threaded surfaces. An o-ring is included that is engageable with a groove in the wall of the ring, and with a slot formed on the inner surface of the duct. The swivel is therefore engageable with at least one end of the body. In fact, the invention is reversible, meaning that the body is formed such that the swivel may be inserted into the other end of the duct to adjust for difference in arbor lengths. A circumferential depression may be formed around the outside surface of the body. One or more bores is formed in the circumferential depression for manipulation with a key. A series of indentations and ridges, or knurled surface, are formed on the outside surface of the body to assist in hand gripping of the system when installed on an arbor.
The advantages and other objects of the present invention, and features of such a self-aligning arbor nut system, will become apparent to those skilled in the art when read in conjunction with the accompanying following description, drawing figures, and appended claims.
The foregoing has outlined broadly the more important features of the invention to better understand the detailed description which follows, and to better understand the contribution of the present invention to the art. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in application to the details of construction, and to the arrangements of the components, provided in the following description or drawing figures. The invention is capable of other embodiments, and of being practiced and carried out in various ways. Also, the phraseology and terminology employed in this disclosure are for purpose of description, and should not be regarded as limiting.
As those skilled in the art will appreciate, the conception on which this disclosure is based readily may be used as a basis for designing other structures, methods, and systems for carrying out the purposes of the present invention. The claims, therefore, include such equivalent constructions to the extent the equivalent constructions do not depart from the spirit and scope of the present invention. Further, the abstract associated with this disclosure is neither intended to define the invention, which is measured by the claims, nor intended to be limiting as to the scope of the invention in any way.
The novel features of this invention, and the invention itself, both as to structure and operation, are best understood from the accompanying drawing, considered in connection with the accompanying description of the drawing, in which similar reference characters refer to similar parts, and in which: